The three-engine Savoia-Marchetti S.M.79 Sparviero ("sparrow hawk") was developed from an eight-seat commercial airliner of 1934. It entered service as a conventional medium bomber with the Regia Aeronautica (Italian Air Force) in 1937. "Volunteer" crews employed the SM79 for the Nationalist (i.e. Fascist) forces during the Spanish Civil War. Also in 1937 the S.M.79 was tested as a torpedo bomber, equipped to launch a single 450mm naval torpedo from an offset rack under the fuselage. Following Italy's entry into the war in June 1940, when 14 stormi (Wing) were equipped with Sparvieri and were based in Italy, Sicily, Sardinia and Libya. The aircraft was more-or-less constantly in action against allied shipping.

You will note, however that the August 1939 cover shows a two engine version. This is the twin-engine export version powered by less reliable Fiat A.80 engines and with a glazed nose for improved bomb-aiming. More economical but slower than the standard SM.79, it had the same armament. Iraq bought five, but this version achieved little success in Italy. This is the "public" version that the artist would have had access to through pictures or film.

Photos of the Savoia-Marchetti S79E and S79
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During the invasion of Crete S.M.79s were active against Allied shipping in the Aegean, after which most aircraft were redeployed to Libya for operations against British naval forces and convoys in the Central Mediterranean as well as the naval base at Malta. Among the ships of the Royal Navy sunk by S.M.79s in the Mediterranean were the destroyers HMS Husky, HMS Jaguar, HMS Legion, and HMS Southwall, while the battleship HMS Malaya and the carriers HMS Indomitable and HMS Victorious were all struck by torpedoes launched by the Italian torpedo bombers; the majority of these ships were hit during the attacks on the Operation 'Pedestal' convoy which sailed with 14 merchant ships and heavy escort for the relief of Malta.

Here is a video of an Italian propaganda film for the Savoia-Marchetti S79 in action: